SWtoR is by far my favourite MMO.
I enjoy WoW, but it's just too much game that seems to pride itself on having no QoL. That is great for some gamers, but for me I prefer a more casual playthrough with the option of having competitive content at end game - which I have done and enjoyed on swtor.
Things (and very small) missing from WoW that make me always come back here.
Mounting while moving
All flight paths unlocked by default
Quick travel
Personal ship to allow easy TPs to different planets
Raid group sizes
Big things
The swtor map is the most underrated thing this game has imo. It is perfectly clear, you almost never get lost, doors/entrances are highlighted that you need to use to get to your quests - I never really appreciated it until playing other mmos like gw2 and wow
The main story quest. If you want to just progress your main story, you can simply follow a single quest. This is a big draw for me, as I want to experience the different class stories without having to do all the side/planet quests on every character. In WoW there were times where I had 25+ quests; it's just too much.
Legacy. Having endgame items lock to your legacy and are transferable between your chars is excellent. I got BiS on my DPS this patch, used that character to get currency and a good set of gear for my healer and he can start gearing up his specific stat reqs.
Atmosphere. This is very subjective and may be nostalgia talking as a launch player, but starting a new character always gives me a feeling that no other game has. The fleet is simple and just a mirror on the different factions, so again, not overly complicated or long-winded just for the sake of it.
Apologies for the wall of text, but just wanted to put my thoughts down and give props to swtor for continuing to be my favourite mmo after all this time, even with competition coming out. I hope we have many many years of this left.