i think the phone is the best for field recordings b/c most likely u are already carrying it in your pocket and its pretty quick to activate.
if u are already catching sounds on your phone, the volca sample is a super great sample mangler & sequencer.
the majority of dedicated field recorders available now are pretty damn cool and most of them have built in fx. but u gotta either have it on always or be ready to pull it out, turn it on, and then record. which admittedly isn't a lot, but sometimes is enough to miss what u wanted to record, or not bother w/ pulling it out in the first place.
if u go sampler, SP sounds like your jam. (starting to feel like a broken record)

they are one of more immediate samplers out there IMHO. not that it doesn't have it quirks.
get a 202 or 404 (or 404sx) to go battery if u wanna bring it around w/ u. altho like i said above, unless u are dedicating a block of time to go around and catch samples. the phone is usually the easiest to actually do in reality.
other samplers to look out for maybe. MICROGRANNY, yamaha SU series, roland ms?, zoom sampletrak. even either of the new-ish mini KP 2's have a recording/"sampling"/storage feature.