With rare exceptions, I always suggest starting with the original. These were the performances worked out by the actors with the original director and the authors in consultation.
With Company both Dean Jones and Larry Kert were issued. Kert's voice was tracked in over Jones and he sounds removed from the action. Sony issued it on CD in the U.K. (and in Canada) but not in the U.S. and it was deleted after about 3 years, so finding copies may be difficult. Do not pay huge amounts for it. Some sellers charge over $100 for a copy and it is not worth it.
As has been mentioned Kert's version of "Bering Alive" is a bonus track on Sony's current CD edition of the Broadway cast. (The original CD edition Columbia CK 3550 was deleted when the reissue came out.)
Of the revivals, for me the 2005 with Esparza is preferable to either the 1995 (Broadway) or 1996 (London) recordings. If pushed get the original Broadway cast CD and the DVD of the 2005 revival.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com