I can't directly compare to Boss, haven't heard their recent modelers enough to have an opinion. Their reputation for not supporting post-release put me off, in this era of Fractal & Line 6 quality long-term support.
If the budget is there, I'd look at Fractal Audio's FM3, it has a lot more metal amp options. I hear waits are still rather long for them, though. Axe-FX III is still the king for guitar amp variety (and arguably, modelling quality).
If you like complicated effected tones, I hear the Boss GT-1000 has the best UI and usability now--things like automagically disabling power amp/speaker modelling depending on what your playback system is, which you can change with a global option, rather than have to edit patches for particular uses. There are some flexibility advantages to Helix, when you are using different outputs for different uses, but for grab & go and not knowing what rig/monitor you'll be plugging into, Boss's approach is less work.
Helix firmware 2.80 will have 67 guitar amp channels includes tons of great metal amps, including models of amps that don't physically exist (Mark V/Recto hybrid, JCM800 with hiwatt power section tweaked for extra bass & sag). Bogner Shiva & Uberschall, Engl Fireball 100, Friedman HBE-100, MESA/Boogie MK IV & Dual Rectifier, PRS Archon, Peavey 5150, Soldano SLO-100, and soon the Revv Generator 120's hottest channel (rest to come in a later update). Line 6's own Badonk, Cartographer, Doom, Elektrik, Epic, 2204 Mod & Fatality shouldn't be overlooked, either. And that's just the list of obvious metal high gainers. And a lot of classic amps from Marshall, Vox and Fender, and broad selection of others. Then there's the 14 bass amps & preamps. 208 effects including 44 distortions.
With effects, it's possible to boost and sculpt many of the amps into almost any sound you want. I've got a patch which includes searing, heavily compressed leads built on top of the Litigator amp model (also does more expected low to midgain sounds from it in other snapshots). Being able to use Mesa's 5 band graphic or a parametric EQ after any amp but before the speaker cab works nicely for rhythm parts.
Only caveat to the Helix is really that the cab modelling treats you like a studio engineer: you have to know what speaker cab you like (that part is usually easy), then what mic (or pair of mics if you go dual cab, which lets you replicate a common recording technique of using 2 microphones) at what distance and with what EQ on each... A lot of people find it more convenient to use IRs (Impulse Responses), which also have the benefit of being switchable per-snapshot without having to use a separate cab model node for each speaker model.
Most modern modellers are great for home recording and bedroom jamming. Helix is a top contender in part because of Helix Native: being able to reamp tracks in your DAW is very powerful. Helix Native is $99 for owners of Helix hardware. Helix Floor, LT or Stomp (in descending capabilities & price) all make great audio interfaces, too.
