Re: Best alternative to Big Sky?
If you want a multi-effects, I'd look at a Line 6 HX Effects, or even the Helix outright [or a Fractal Audio AX8 or FX8]. Helix series have a great collection of effects, with more coming periodically. Line 6 employees recently confirmed they hired a team of polyphonic pitch shifter experts... And they have a lot of other improvements in the works. Though it's already pretty strong, until then you may have to stack or run parallel delays/reverbs to get lusher sounds that don't overwhelm.
I'm impressed by how good the recently added legacy effects are. Legacy effects being the ones ported from older models to the Helix line. I've recently been going wild with fuzzes--Muff and Tone Bender are different beasts when you add treble/mid/bass controls. I prefer many of the legacy algorithms to the designed-for-Helix ones, not because they sound better at modelling the device they are based on, but because of the extra features (lower CPU/DSP use is also handy for being able to have a wide selection of effects in one patch, even if you only use a few at a time).
And then there's the new amps. I'd managed to avoid finding out just how fun the Friedman BE-100 is to play until Helix 2.50.
I have Helix Native, but no personal experience with the floorboard or rack version and how much floorboard space they'd take up. [Only thing Native is seriously missing, at least with my cheap audio IO, is selectable input impedance which is needed for perfect behavior with different pickups/effects/amps. IMO they ought to do a good computer interface that supports the floor controller from the rack version.]
If portability is a bigger issue, PFDarkside's advice about verb/delay plus mod pedals is close to what I keep running across on effects forums [heck, there are some people who use them with a Helix, though many are ditching them now that Helix has more options].