Well, 2nd is like night and day with all the changes so my thoughts on what I like:
1) Low model count, Threshold is usually 3 or so models and the Lurker could be a bit more.
2) Quick games,once you know the rules well about 30-45 mins for a game.
3) The new solo deck and rules option is very appealing as it is sometimes hard to get together with the only other SA player at times, life happens for each of us so this allows you to enjoy the game.
4) Options, options and options...game in 2nd has much more variety, Theshold has more variety i skills, options of gear and team choices. Same for Lurkers with more monsters, weapon options, relics, scenes of horror and more. Tons more scenarios.
To me it is one of the best skirmish games out there.