As already said, Frostgrave and SBH are two quite different games.
I love SBH, and albeit I have some personal grief vs the system as the author has gone a bit too far on trying to sell the same game over and over again, imho, sometimes with very minimum changes, I cannot avoid to suggest it as the activation system alone makes it worth playing. Also, while combat system seems a bit too simple and random on the outcome at first, it has quite some depth instead (move a model behind the intended target prior attacking it, so to convert a
push result into a
ko one, keep one model ready to dispatch an enemy that eventually falls down, etc - this mixed with the activation system leads to some pretty hard choice). It's really a great little system. It also contains campaign rules, but they're VERY basic. I'd go for the non-Advanced one, as from the Advanced I like just the reaction system (that you can get from
A Fistful of Kung Fu, too - one of the spin-off games I like the most). Other stuff just clutters an otherwise very straightforward game.
On Frostgrave, I'm currently playing a campaign. Best thing -for me- is the setting: very suggestive. Rules are light and very focused on campaign. So I wouldn't suggest Frostgrave if you're not interested or can't play a serie of linked games, as that's it the heart of the system. Lighter than Mordheim's, but way more detailed of the SBH one, the campaign is the reason to play this kind of game. Unfortunately, my actual fellow players aren't interested in the modeling aspect of gaming, so they're playing with prepainted D&D minis I lend to them, but otherwise the other great thing of playing a camapign game on, say, weekly basis, it's that it also engage you even in-between games: first-of-all, as you have to plan and update your band. Also, last Mordheim campaign we played (4 players) we had a constant exchange of modeling/painting progress pics on Whatsapp along with brags, jokes and taunts, thus giving us the feel to get more from the game than a single game per week.
So, for spot games, especially if you plan to engage people who doesn't usually play (or don't own their own minis) I'd go for SBH. If you're confident you're be able to play with engaged people on a somewhat regular basis, I'd go for Frostgrave. This said, as alrerady said by many, both rulesets are quite affordable, and you'll be able to use most of the minis in both games, so getting both wouldn't be a bad idea at all
@hubbabubba: yes Otherword is based on 7tv
reaction systrem, and it seems it's directly compatible with the 'fantasy' spin-off 7th Voyage. ALbeit I wn 7th Voyage, I haven't managed to play it yet. So can't tell much more, sorry.