Here is my take, and I will come right out and tell people I play Merge myself, so there is probably some small bias there ofc.
If you want to play 1-2 tables and don't care about tracking your play or using a HUD or MORE IMPORTANTLY LEARNING TO USE A HUD OR REVIEW YOUR
hands, than Bovada is a good fit. You get soft competition, and if you just wanna play 1/2 tables of cash or one donkament at a time, I think it's probably the best or @#2 option out there.
They pay out fast , and have been in the industry for awhile.
The flip side of Bovada is Merge. Merge is good with both donkaments (great size/GTDs/Schedule) and also has very good cash liquidity up to 3/6 NLH and a decent amount of LHE (dont quote me, it's been awhile.). The best advantage Merge/Carbon has is software. THE MERGE SOFTWARE IS A JOY TO USE and as close to
pokerstars/FTP level you are going to get. They also offer mobile play which has had rave reviews I hear. You can use a HUD and track your play, but EVERYONE AT MERGE has the option of playing with an inhouse HUD, so you can learn to use one free!!!
Ok, now for the one HUGE pitfall at Merge, and I won't pretty it up:
YOU WILL WAIT A LONG TIME FOR CASHOUTS AT MERGE, PERIOD.
I have withdrew 3 times....and only once was it within 4 weeks. That's the deal; its been known and it's been the deal for a long time. THEY ALWAYS CASHOUT, but it takes about 3/4 weeks longer on average to get it.
If you don't play for a living this is basically an inconvenience....
If you play for a living, I wouldn't play Merge primarily bc of this reason.
WPN, well, WPN was growing, but it's pretty much plateaued according to the pokerscout data I see. It is compatible with the big 2 HUDs, and you can multitable.
The biggest edge WPN has is it offers a rakeback program somewhere around 30%, I forgot.
The biggest drawbacks compared to say Merge would be less liquidity, a far INFERIOR MTT schedule (if you love MTTs, it's not even close, it's Merge all the way between those two) and the software at WPN is just LOLBAD.
Honestly the software is like tilting...bad. They do run a lot of like jackpot stuff....promotions, etc, but honestly it's mostly stuff that doesn't really add value imo. I could be wrong, but...that's my perception.
I'd say it's a good option if you NEED HUD availability and want to mass table / utilize rake back a ton.
Other than that, I don't think the other sites offer much in the domestic, grey market area US.