Wet-test both and make sure to focus on things you'll be living with for years: seat comfort/angles, jets, adjustable valves, buttons/controls, and noise level.
Ozone by itself is not a primary sanitizer, but more of a secondary oxidizer. On a frequently used tub, an effective ozone generator can help oxidize bather waste (sweat, etc) reducing your chlorine consumption by perhaps 50%. One an infrequently used tub, ozone will break chlorine down causing an overall increase in chlorine consumption. Keep in mind chlorine is a perfectly fine oxidizer and residual sanitizer all in one, so ozone is of debatable utility.
Ozone can also work well in conjunction with a bromine-sanitized tub by reactivating the spent bromine, but usually there isn't enough control of when the ozone generator comes online to really dial that in well.
Salt-water systems (SWG) are still chlorine based, just that they continuously convert salt (sodium chloride) into free chlorine. Most of these systems are far from automatic or hands-free. You must adjust the run time (duty cycle) to more-or-less match your tub size and bather load. Most of these systems offer a "boost" function to use after soaking to help oxidize bather waste. In my experience, boost mode works for light loads, like two people who shower before soaking. It is no match for a sudden heavy load like a bunch of kids. One time a slug crawled into my tub and crashed the chlorine level. The salt-water cell wasn't able to overpower it and the water went bad while I was away. You can manually also add chlorine after soaking and just use the salt water generator as a constant background level, which is handy when the tub isn't used for a week or so. It also helps to have some stabilizer (aka CYA) in the tub, so I would manually dose with dichlor for the first week before adding salt and switching on the SWG.
Like a number of brands, Bullfrog now ships standard with the Frog @ease SmartChlor system. This also maintains a low-level of chlorine, plus silver ions. Similar to a salt water system, you need to dial-in the output to match your tub size and average bather load. I have found it less fiddly than the SWG, though. That convenience comes at a cost,... about $360/year in cartridges.
If you don't mind testing and dosing your water every day or so, it's hard to beat the low cost and sparkling pure results dichlor-then-bleach method of water care. Look it up. Just beware that most shops would rather sell you high priced bottles of chemicals and will thus have lots of nonsense reasons why you shouldn't believe "things you read on the internet." For my previous tub with SWG, I used ordinary pickling salt (no additives), much to my pool store's horror that really wanted to sell me expensive bags of certified pool salt.
All that said, I've now owned both Bullfrog and Hot Springs tubs. Both are very nice.
My old HS Jetsetter basically rotted away due to the wood base and frame and attracted a family of rodents, but it did take 15 years of rainy Pacific Northwest weather. Over its lifetime, the Hot Spring tub went through two heaters, one jet pump rebuild, a moto-massage unit, spinner jet, pillow, and various repairs to the cabinet as time took its toll. I was its second owner, so who knows what water balance abuse it went through before. I did all the work on it myself and sourced parts from Back Yard Plus.
My new Bullfrog A5L is a huge step up, but I would expect Hot Springs to have improved as well. I like that the Bullfrog has a heavy duty plastic base and frame, and the parts are less expensive and more commonly available. The swappable Jet Packs are pretty neat and do greatly reduce plumbing complexity and therefor potential leak points. My delivery tech has seen them all, currently owned a Hot Springs, but said his next tub with be a Bullfrog, just based on the plumbing alone. Take that for whatever it's worth. Never had a plumbing leak on my Hot Springs.
