Helix Floor bass player here.
I was using a normal bass amp + bass cabs and didn't like that the range of sounds was limited by those two elements in my chain. I tried using a laptop and Amplitube for a while, but it was too unstable - the application crashing in the middle of a gig is something you don't want to experience twice. I was also using a Boss GT-10B multieffect at that time and I liked the idea of having a single unit that I just have to hook up and go.
An Axe FX was too expensive and seemed like overkill since I don't want to model any real amps as accurately as possible, but just have a "good" sound and enough options to customize it. Units like the Avid Eleven focused too much on guitars. I thought about building my own rack with a Mesa Triaxis. but the FX and MIDI switching efforts would have made that project huge. I liked the idea of something like a Triaxis though since I work a lot with overdriven and distorted sounds. I also tinker a lot with my instrument.
The Helix seemed a natural choice for me: My band needed a PA anyways, the Helix can simulate any cabinet I can think of (via IR) so I'm not limited to a single tone anymore. I can simulate guitar amps and bass amps, mix them, EQ them and switch them all with a single button. And I can take that entire collection of amps and setups home and spend hours finding the perfect gain setting instead of annoying my bandmates with it.
So much for myself. Now, I would generally recommend a Helix in two cases:
1. If you don't want to carry and maintain (tube amps!) a real amp. Depending on where you gig you may still have to carry a PA and/or monitor. In a large enough place you won't need that either, instead you'd have a single unit. The FOH guy is also happy because he can right away get a clean DI signal.
2. If you want versatility. If you regularly switch between a vintage Ampeg rig, a modern Mesa into a 4x10 and an overdriven Marshall, this is the right tool for the job. Also if you have FX pedals or rackmount units that you want to keep using by taking advantage of the Helix' FX loops.
If you are more happy with an actual amp for whatever reason and/or you don't need that much variety, I would recommend getting something smaller instead to save money. A Helix might also not be ideal for those who really dislike too many options, buttons, knobs etc. - If you prefer a tone knob over a 10-band EQ, the Helix could become annoying.
Another aspect is the bass pod you mentioned. I did not have one, but the Helix definitely sounds better than my GT-10B. I would assume it's an upgrade to the bass pod as well.
You've already mentioned in your post that you don't have any pedals that could go into the FX loop and that you prefer to not use your own amp, but I thought I'd still list those things for the sake of a complete opinion. I cannot offer any advice on Floor vs. LT though. I got mine when there was no LT available yet, and I would still prefer it for versatility.
[Edit] What I forgot: The Helix didn't have many bass amps when it came out, but their number has been constantly increasing. And that's the big difference to most other multi FX and ampsims, at least when I made my decision for the Helix. So don't be tempted to think that the Helix is a guitar unit and also has a bit of bass stuff thrown in because someone at marketing said "it's necessary". I use it exclusively for bass and never felt like I'm not the target audience for this unit. It's something I'd like to give Line6 big credit for, it's one of the few products made for creative bassists.