In "My Opinion", and Experience with both classes(mainly my playing style), Ranger is a better choice.
Pve Ranger: Can Soft Cap Range Attack Speed, good crits, fair evade, can easily stun lock quest bosses for easy solo'ing, and keep any mob from getting close into close range, High Hit Rate. all these helped me progress with a Ranger/SharpShooter(SS), talent changing on situations gives the most useage out of your class. as for melee capability we have talents that allows us to change from a Ranger to a melee-ranger in second (Sword Spec + Art of denfense) which can also allow us to solo dungeons such as ACV when equipped with certain armor(pvp sets, and lvl65 sprite set, leech sword, 66bow) while maintaining high evade boost from melee talent combo. by time your lvl60 in melee mode, you can have up to 70% sword damage easy which is a huge boost to your strength. our downfall to being a melee ranger/SS is the lack of skill, and close range attack speed. we only have 4 melee skills(that's including the novice skills).
A PVE ranger in Action(MCM mob solo'ing)
PVP Ranger: Yes it's true we can't restealth once in battle mode, but who cares, again we can soft cap the attack speed, we have Anti-stun(Mongoose reflex) only last 5seconds, but helps, and that 5seconds can easily be increased with PVP sets, and the lvl65 sprite set, and lvl80 orange/yellow set, which means longer Anti-stun with 70-75% evade boost. we're a sin's worst enemy in pvp other than zerks, and paladins. because rangers are one of the only classes that can max their attack speed with no problem, may it be using the Level28 NT bow proc, with Watchkeeper Proc. that proc combo give +150% hit rate, your never missing your target no matter if the sin's Evade was to hit over 200. not to forget that watchkeeper also gives a +50% attack speed boost to bow attack. so we're deadly, rangers are very good at capturing the crystal, and protecting, and 1 on 1 fights 9/10chances a ranger can win with minor problems, a well built ranger will need to get ganged by 2 or more people jsut to go down. want to see how good pro rangers do in arena then watch
this , or
this , or
this , or
this , and lastly
this
These vids show how a ranger should play in PVP, and how good they really are.
my personal build for ranger both PVE/PVP from level31-48 i use
Flaming Fang + Sword of Dawn for sword, +20% chance of double hit on both swords(not expected to get into much close range fighting so these swords are your friends) note: that doublt/triple hit percentage doesn't stack, they act individually,
Eye of the Heart Bow(level28 NT bow)(10% chance activate weapon ability when attacking Ability: Long-Range Hit +100% for 20 sec), and
Watchkeeper's Bow(Level38 NT bow)(+4% chance to hit When physically attacking 10% chance to cause Beast 462 DMG 12% chance to activate weapon ability when attacking Ability: Bow Attack Speed +50%, Long-Range Hit +20% Lasts 20 sec.).
For armor some ranger's use Ranger Legacy(b/c of the HP boost it gives), but i prefered to use Hawkeye Set + lvl34 Blue helm(b/c of the crit damage boost, and skill boost, also prefix boost depending on what i want for a prefix: Evasive, Perservering are probly the prefix you want on your orange armor. For weapons, Deadly, Death, Swift, and Accuracy are your best bet), a cape with sleep effect was my choice to stop alot of people from ganging me, and cut their DPS, but cape choice is yours.
From old experience with Assassin
Sin Pve: fast melee attack speed, high evade if they know how toggle their buffs, can stealth when ever they want basically. can change to range easily(but of course not a better range fighter than ranger). Can Solo ACV much faster than a Ranger/SS, due to them being built for close range.
i haven't pvp'ed as an assassin much, but i've seen most in lvl40 arena use 2 nightmare wraths, miracle bow(+4% chance to hit
8% chance to activate weapon ability when attacking Ability: Restore 625-1250 HP to yourself, Movement Speed +10%, for 30 sec), Watchkeeper(for shooting down runners) or assassin fingers(When equipped, Evasion +15%), and i personally believe they use Ambush set for the evade boost.(personally don't know some people choose sin legacy for pvp over ambush. if they want more HP they should get the lvl36 blue swords, and change the prefix until it gives a lot VIT), as they get higher level in PVP i think they start to fall, and get suckier, not saying their damage out put sucks, but other classes get much better then sins, for example: Level 70 arena.
Temps can obtain anti-stun with the lvl65 pvp set, lvl50 shield yellow shield(100% crit proc), lvl68/70 relic(-100% magic damage received when procs) high Defense(so for physical classes they have to gang and hope to take it out quick, or leave for magic classes to fight alone), and Leech Sword, 60/65axe, 60/70hammer can be used for DS pwn'ing, not to mentioned that magic attack they use for pulling can now stun, and very good built Temps can hit through Evade very easy.
WL can achieve Pure Raw Damage, Bullcharge is 100% hit, with stun(stun throws Evade to 0) so a DS would crumble fast, most WL will have high attack speed, and very good WL can crit very often, and high, they can have good Defense, but not as good as a Temp, so their is a chance a DS can kill one, but not to often unless the DS is very good. WL have Leech sword, Sleep hammer(used for defensive reasons), seen some use Lvl50 yellow shield for crit proc, and will use 70 1-h axe can also leech HP, but they can also use lvl65 axe for more damage. lvl68 orange gun for +55% crit damage, which can play a big part to maxing out crit damage for WL(bored from gaia is a perfect example for very good built WL) a WL can also use the lvl65 2-hand sword(which gives an anti-stun proc).
Sharpshooters in 70 arena will use 65sprite set, or 65 pvp. mostly for the mongoose time boost which give 17-25 seconds of mongoose(anti-stun + 75% evade), Level 70 leech sword, and lvl60 Triple Hit sword, combo'ed with lvl60 Bahado's Hero Gun(+15% Chance to hit 12% Chance of firearm damage +100% for 8 seconds) for proc'ing with the Lvl70 Northland Scion - Scorched Sky(+18% chance to hit 12% Chance to activate weapon ability when attacking Ability: Firearm Attack Speed +50%, Long-Range Hit +45% Lasts for 20 sec) this is scary for a DS, being that a SS built good, and having these gun means +100% damage, 100% hit rate, and maxed firearm attack speed, not to forget they can leech HP, and also lay on Triple hits. so a DS won't be dodging any attacks from a SS with these proc'ed on, and a SS having anti-stun on for so long, can be an issue, for more than 1 reason.-> Paintball effect(prevents shadow slipping, Rooting in place(can make it a range fight, just by keeping you in place). they have the advantage. same as WL, they can use the lvl65 2-hand sword for anti-stun proc, but not many use it.
Darkstalkers in 70 arena i seen use lvl70sword(leech sword), level 70 bow(+20% evade), lvl65 yellow sword, level65 pvp set, or lvl70 sprite set. not going to talk about this much.
ArchMage, and Demonologist: high magic damage from both, but not talking about these much, only thing needed to be said here is: Level70 Staff... Anti-stun.
Mystic will use 65 pvp for triple hitting, lvl70 staff for bird form, and sleep hammer(lvl70 yellow), with either lvl60/65 hammers. some will use 70 set as well.
Prophet: might use lvl70 shield(+100% magic crit, and -100% casting speed), or lvl65 shield(randomly removes any debuff), lvl65 staff(+200INT -50% casting speed), Lvl70 staff(anti-stun), lvl70hammer(sleep hammer), for armor lvl65 pvp set, and lvl70 set.
Point being that in lvl70 arena DS is at an disadvantage for so many classes getting Anti-stun, and high hit allowing classes to hit through Evade in pvp. but altogether it's still a good class like all classes all, it all comes down to build, playing style, skill, equips, etc.