This raised a chuckle from me. Years ago, I went amp shopping, asked what the Marshalls were like, and the guy in the store - trying his sales pitch - gave me a full on "Oh, you'll love this, they're great for that Guns 'n' Roses sound." He looked aghast when I said "oh, oh dear. Have you got something else, then?" Horses for courses.
My sonic tastes have moved sharply away from Marshall in the last twenty years, but I never found their quality lacking. Main thing I'd suggest is - if and when possible -go to a guitar store and try as many different amps as you can with *your* guitar. Some maps work great with some guitars, others less so.
The Valvestate range are pretty good at capturing the "Marshall Sound" as far as I remember, though there are also plenty of alternatives out there, especially with modelling amps now. Buy the sound you like, though - don't fall for perceived versatility if you know for sure there's only one sound you'll ever use. Equally, the point above about 100watters is well made. Literally nobody needs 100watts nowadays. You'll only end up with an expensive looking bit of novelty furniture you can't play in the house. IMO, 5 tube watts (10-15solid state) is plenty loud enough unless you're playing with a drummer and no PA. I have one of the older Vox Valvetronix 120w models, size of an AC30, capable of 2 x 60w in stereo. I've never played it higher than the 2 x 1watt setting in the house. Big maps are overrated; in ten years time, I expect amps will start to disappear from stages, mostly replaced by preamp pedals into the House pa. Already happens more often than you'd think.