The tanks are good but their protein skimmer and lights are not the best generally TMC are better at making tanks than ancillary equipment. I personally prefer Deltec protein skimmer and Ecotec Radion or GHL Mitras for lights but these are more on the premium end of the scale so more expensive but you are buying into their ecosystem.
Their sump/weir and return pump arrangement are logical and sure beats making a custom sump like I did for my tank( was a pain in the backside) and on the 90 its quite spacious too. Just make sure you do not spill water when cleaning or changing water, as the laminated wood can get damaged, but I believe they have waterproof bottom, apart from that they are decent tank. The RO reservoir is quite decent sized on 90 just need to decide if you want to buy automatic RO topup system which is either float or sensor based. I did not trust either so had a controller as backup because I had one get jammed once and dump large amount of RO water into my system.