I don't regret any Kato loco I've purchased. I consider it money well spent, E8A/B, P42 (x2), F7A/B, SD45, SD70 (x2) but can't say that about anything else, but some of my Lifelike's were very good values, SD7, PA/B, E7A/B, SW900/1200 (x2), E6A/B, F40PH (x2), FA2/FB2, and FA1/FB1. My Atlas SD60M's are nice, but I sure don't like my SD35's or GP9TT, the SD50 set was not as good as the SD60 set. The Atlas have nice detail in painted handrails, look better than Kato. Like the F59PHI set, nothing wrong with that, should have white headlights tho'. I tried Model power cars a couple of years ago, too light, LL cars in a set, too light. MT cars are great if your couplers match, recent Atlas cars are nice. Wasn't that happy with ConCor cars bought at LHS, ordered a smoothside passenger set, trucks bind, not enough weight, the Riverossi heavyweight wheels squeek and coupler hight seems off for most other locos. I'm very happy with my Kato passenger, Lark (even if not matching the prototype, looks nice and I like it, it was the first passenger set I could get), and my Kato Budds and Superliners look great, run great. My Bachmann F7A/B sound terrible, it hurts to hear them run (sorta like the GP9TT), no slow speed, but they look nice, and do seem to run, as does the Main Street Trolley. There are some LL around marked F7, but they must be on FA2 chassis, look nice, sound good running, just a bit too long and no B unit. Junk rolling stock needs work and weight, wheels squeek, drag like the brakes are set, and the Rapido couplers are way too big, sag, come loose.
You always pay for what you get, but you don't always get what you pay for, quality in some lines seems inconsistant, a good set of both numbers in one model run doesn't mean nearly the same thing in another run will be good.
My PA/PB LL sets from N scale supply sure seem better than the same model in a different roadname purchased locally or from another dealer. Was someone cherry picking? About $60 each for good ones w/o B, $35 for the lesser ones, including dummy B.
If you plan on living a while, running the same trains, the good stuff is worth it, and if the price is right, LL is a good value, even the GP38 models run nice, gave me a chance to double then triple head for $20 each for the 2nd two.