It depends very much on the application you're going to put it to. -
For prone / bench shooting the old fashioned folding target scope stands are great & are hard to beat - I use one with an old heavy duty pan & tilt head on it. Rock solid & will hold the heaviest scope.
For standing up viewing, the Manfrotto 055 tripod (£45 new on ebay for the basic ones, a bit more for the ones with tilt flexibility in the centre column adjustment) married to a heavy duty ball head with QD top plate (15 or 20Kg capacity again on ebay about £20) is a very good option, again very solid & these new ball heads are very smooth & secure.
Fluid heads are great but strong ones cost a fortune even second hand!
The type of spotting scope again determines which tripod to go for -- Straight in line eyepiece scopes need a much higher tripod than the angled ones.
Get the heaviest rated tripod & mount that you can comfortably carry - lightweight ones are too flexible & prone to vibration.
Ian