Zone 4 is good for multisport (triathlon and its offshoots), XC ski/bike and other mass start events.
Split Second Timing is a good avenue to consider for alpine ski racing since it requires little commitment - a licence can be bought for as little as a 30 day period, and the majority of the software is available free for assessment and registration purposes. It's well sorted for FIS sanctioned events and the included Club version contains much versatility. SST also has a free live timing utility for easy instant results streaming. I'd be reluctant to use it for MTB DH unless the number of competitors on course can be restricted to 2 or 3 like in ski racing, or long (90 sec or more) intervals can be applied.
The Canadian dTris/Measures system is focused on ski racing as well, and it's a good bit less expensive than Split Second (no free live timing though). Like SST, it can handle multiple intervals and speed traps, and there is an optional utility for data output to remote display/announcer screen.
Vola has a lot of bells and whistles but costs accordingly if you add the various modules for different sports. It can drive data to video production if that has interest, but do you want to pay for it? And Vola is a box purchase that stays active more or less indefinitely, you have to commit and then make it work from there.
As Fred said, there's no single solution for all applications. Talk to timers working in events you're interested in, and see what products work for them. Talk to the vendors, they are pretty accessible and happy to take phone calls for all your questions.