I think it depends on the people you RP with. People use a variety of methods to resolve RP fights. There’s advantages and disadvantages to both. I’ll outline them below. If anyone has anything to add, please do so! This is just what I’ve observed - my personal perspective.
Roll fighting:
As the first you’ve mentioned, I’ll do this first. Roll fighting is the procedure whereby the outcome of a fight is decided by a /roll in game, which generates a random number between 1 and 100 (unless another number is specified). Often these fights use several rounds of rolling - the most common one on one fight system I’ve encountered is one where Person A attacks, and rolls. Person B rolls defence. Then the rolls switch, Person B rolls attack, and Person A defends.
Advantages:
- Fairness/balanced playing field. Nobody can godmod or RP an undefeatable character. In one way or another, each participant has the potential to lose. In a sense it ensures that everyone has a fair chance of winning.
- Alt-friendly. You can win a roll duel even if your character is lower level, or undergeared. This is good for people who like RPing their alts!
Disadvantages:
- Lengthy. Roll duels can go on forever sometimes. A PvP resolution is much quicker that’s for sure.
- TOO balanced. Sometimes it can feel unsatisfying if the highly experienced warrior character loses to Jimmy the stable boy who only knows how to wield a shovel! The rolls even the playing field, but sometimes this might not align with what makes sense ICly. (That said I’d say even the most powerful characters might occasionally lose, even through sheer dumb luck!)
PvP duels:
Self explanatory really. This method of fighting is a simple use of the gameplay. PvP combat!
Advantages:
- Looks good. PvP duels look GREAT! Nothing quite matches the visual of an actual PvP duel, as opposed to just standing still with weapons drawn. From a visual standpoint, PvP duels look the coolest.
- Speedy. PvP duels are fast-paced. The fight is done in less than a minute, usually, freeing up RP time!
Disadvantages:
- VERY Unbalanced. PvP dueling on your main is a lot of fun… but it sucks to be on an alt or low level toon. If Jimmy the Stable Boy is level 120 and Algazor, Arch-Warlock of Argus is level 110, well… Jimmy’s going to win every time. Too bad so sad. Additionally gear is very important. Hardcore PvPers are going to have a huge advantage over even more casual players, level 120 or not. In that sense it can be a tad unfair on your RP character and their perceived power-level.
Pure Emote Fighting
Pure emote fighting is basically just typing the actions of your RP into chat. No PvP, no Rolls, no mechanics of any kind. One simply emotes and responds to emotes, much like they would in a casual chat RP.
Advantages:
- Complete creative freedom. You know your character best; their strengths, their weaknesses… You have complete creative freedom, irrespective of OOC gear/level/etc. With pure emote fighting the world is your oyster, and your imagination can run wild!
Disadvantages:
- Potential for godmodding. The whole reason roll fights exist, in my opinion, is to prevent this. Godmodding is an issue where someone sees their character as unstoppable in every way. In RP fights such as these, they’ll dodge every bullet, stop the enemy’s blade with only their left pinky, and eat enemy spells only to shoot them right out their backside and blow their opponent into tiny pieces! The godmodder is invicincible! Unfortunately this can be unsatisfying for RPers, as they are subject to someone who is impossible to defeat, meaning either THEY need to concede defeat to the godmodder every time (thus inflating the godmodder’s ego further) OR they need to leave the RP fight entirely, because it’s not fair. Neither option is particularly fun. With that in mind… you need to know who to trust in order to use this style.
Me? I’ve used all 3 over the course of my RP. With close trusted friends? I tend to lean towards emote fighting. With randos or acquaintences? I prefer roll fights. Personally I avoid PvP fights because I like RPing alts and frankly I’m a casual player with sub optimal gear. 
But I’ve done them here and there, and so long as you’re RELATIVELY evenly matched, it’s a lot of fun. Pretty sucky if you’re on an alt though.
I guess the point of this, Korvolas? You’ll find people on the server who use all 3 fight methods. You’ll find people who only do PvP duels, or only do roll fights and so on. Ask around. Look for guilds with an RP-PvP focus. The link below will lead you to the Guild directory - have a look around for guilds that fit what you’d like 
WrA Information & Directories (Guilds | Communities | Events)
It’s a big server, Korvolas. And a good one at that! You’ll find people who want to RP the same way as you for sure.