So a bit of history on both lines.
Weekend Warrior was started by Mark Warmoth, you could say hew was the inventor of the Toy Hauler but he wasn't really, but he did bring the Toy Hauler movement front and center, not only did he sell them he was active in the community. WW grew fast, probably to fast, and then the recession hit. WW ran into a major problem with some units that resulted in a class action lawsuit, much of that is documented here. WW went bankrupt. Mark Warmoth went on to take over another RV company he owned, and that company has since merged or bought out by Omega RV. You will also see another RV company selling under the WW name, there is a fight over who owns the name but that 2nd company only sells direct now. Bottom Line: Yes WW had issues, some bad units and left some owners hanging, some have very bad feelings about Mark Warmoth and that's understandable. I can't say I see a lot of new WW owners join this forum, I'm not sure how many are being sold today, definitely not as popular as they once were.
Genesis/MPV/ThorCA, ThorCA was a division of Thor sold to MPV, which then went belly up and was bought by Genesis. The whole era of MPV was like a bad 90s made for TV movie with a crazy CEO and some Chinese investors. There have been some odd tire wear/axle issues with the Genesis RVs in some cases, hard to say how wide spread but I've seen it pop up over the years. Bottom line: They've shed a lot of their past issues, but not a wildly popular line but does have a number of different options, all they sell are Toy Haulers.
As for which, I can't say as I haven't really looked at both. I will say that Mark is very involved in the new WW from my understanding. Doing a detailed inspecting BEFORE you buy (sign for the loan) is important for any RV. If you want links to various owner PDI's we can help.
Two Wire Fox Terriers; Sarge & Sully
2007 Winnebago Sightseer 35J
2020 Jeep Gladiator Rubicon