This is essentially the only one I spend time on. I have a membership at SCF but didn't enjoy it all that much. Have not logged in in several years.
Beckett is a waste. I had a log in there but they say there is no record of me. Not even blocked, Must have purged me. I won't waste my time there.
Don't really like Blowout. They've done some good work on that forum in exposing the scams in graded cards, but the company did me wrong so I don't really give them the time of the day. (If anyone is wondering, I bought something from the company, but part of it was opened and had some of the cards stolen. They offered a $5 credit on a $20 blaster and then refused to even honor that until I showed them a screencap of the email saying they would. I have not bought from them since. Not saying I won't again if they have something I need at a competitive/good price, but...I don't really look often either) I'm not sure if I ever registered on the forum there or not.
Never heard of the others you mentioned.
I very much miss Trader Retreat. I joined that forum in either 2000 or 2001 and had some great times- and some great trades. I dialed back some when I got taken in a trade and they didn't do anything to fix it...not even force the guy to apologize. He eventually got banned for cursing out the admin in their chatroom. Should have listened to me. That was a daily check for me from when I joined until 2005 or 06. I wish I could find my old feedback on there...or at least my Member of the Month badges. I didn't know how to make screencaps at the time or else I would have had them. I think I won twice, which is surprising as I was nowhere near as well funded as most of the people on there.
NUTS (NASCAR Underground Trading Society) is great for NASCAR cards but there's hardly any activity. I can check it once a year and read everything I've missed in 20 minutes. Many people left when Press Pass closed and never came back, which I can't understand, because the love of the sport isn't tied to any card company. It's very hard/frustrating to read because they have it set to that every single word starts with a capital letter. I'm not always great at typing and grammar but that is just too jarring. I joined in 2009 and it was a daily check until around 2012/2013.
I also miss the Non-Sports Card Forum. It, like NUTS, had very little activity, I checked in about once a month. Then it was gone. It was the only place where non-sports cards were discussed as the main focus, not just an afterthought to sports cards. The card companies even announced new releases on there and occasionally gave away promo cards.
I will occasionally pop in to the Collector's Universe forum, but there's very little collecting there...it's almost all speculation. Not a total surprise as it's owned by a grading company, but it's not particularly enjoyable for me. I also take part in the coin forum there, which is another hobby of mine, although a long-neglected one. The World Coin section used to have a lot more activity but it's my favorite. I've been a member of that forum since 2008, making it the second longest I've stayed an active member of any forum, although "active" is debatable as I go months without commenting or even visiting. My first longest is a model car forum which I have been active on since late 2000 or 2001. (2000 is when my family got internet access) It's been several months now since I've logged in there too though. However, I still consider myself a member. 95% of my facebook interaction is with people from that forum and the one it spun out of.
I have very little interaction with anyone from the card hobby outside of this forum. Of course, I am not totally surprised by that either, because...you all know who I am.
VERY slow trading due to health problems. Not transferrable so safe to trade with, just moving is painful and can't always access the cards.
Cardboard History My COMC
New Collection Website: Cardboard History Gallery (Still under construction)
Tips on how to make your scans look like the card does in hand (No more washed out, fuzzy scans!):