We bought a CalSpa 740 'Baja' a little over a year ago and have been very happy with it. We skipped a lot of the 'foo-foo', so it's a fairly basic model, but it's been rock solid. I tend to think that the more 'fluff' you have, the more things you have to go wrong. We don't have bluetooth speakers or magic-saniflow-ozonators or anything like that. Its a big bathtub with heaters and a couple big honking pumps

. We had one issue right after initial install with a cracked fitting, they had a new part overnighted and our installer fitted it a couple days later. Since then, no issues. Came with a 5 year warranty, so didn't cost us a penny.
During the cooler months we use it pretty much every day, sometimes twice a day (in the warmer months we're in the pool!). Insulation and efficiency seems pretty good - we have a sturdy cover with an 'easy lift' thingy, and keep it covered unless we use it. We decided against the 'bench' seat model, gained the extra deep-well seat. Comfortably seats 4 adults, 6 if you're real friendly, 4 + 3kids is doable but water levels are not 'self-leveling'. Most of the time its just the wife and I, so we know how much we displace, and have the level maxed out accordingly. It does have a drain hose built in, but can't say I've ever used it.
We're in mid-Michigan, so it's not unusual for it to be well below freezing outside at this time of year...but I've never really noticed a huge increase in my electric bill - its a 5KW heater, plus the jet-pumps, but they only really run when you're in it, or it needs heating. As most of the heat escapes from the surface and the top has a big insulated cover, your heating is minimal once it's up to temp. The sides are all insulated internally with foam.
Covered, it'll take a considerable amount of time to lose any significant temp, I know i set it to 80F once, and two days later it was still in the 90s...so we generally leave it on 104F pretty much all the time unless we're going to be away for a week or something. Didn't seem like much point dropping the temp and then raising it again before we wanted to use it (and we'd probably forget and then its not ready when you need it etc). I'm sure other models probably have wifi apps or something where you could setup a schedule for heat/cool, but we just like it being ready whenever we want it. There is a dusting of snow on the top of the cover right now, and it last snowed about this time yesterday, so that gives you an idea on how well the insulation works
As for quality versus other brands, I can't really say. It does use 'generic' parts like Balboa, so in theory it's fairly easy to get spare parts. For us, the 5 year warranty took most of the worry out of it. It seems solid enough, I notice the odd rattle from the outside cover which is normally solved just by tightening one of the access panel screws - I could probably add a little silicone in the screwhole to stop it vibrating lose, but that's about only 'quality' thing I've found that is even worth mentioning. Filters are standard sized, so they are available on Amazon for reasonable prices..so reasonable that I rarely clean them, I just replace them.