Celtic
Play in front of an average crowd of 49,000 at home, away from home play in front of attendances ranging from 2,000 - 14,000 apart from Ranger's games.
Be in Europe every season and occasionally doing well, mostly going out quickly to a poor team and call them cheats.
Be involved in controversy such as scum fans, threatening to kill their fellow Glaswegians.
Effectively ruin your career by staying there because of the poor reputation of the league (below Cyprus and Israel in European performance)
Southampton
Play in the best supported 2nd tier league in the world and one of the best supported leagues in Europe.
Have a chance of playing against big clubs such as Leeds, Nottingham Forest, West Ham, Hull City and probably more when they inevitably get relegated.
Average attendance of 17,000 in the 2010/2011 season, will have risen since Southampton, West Ham, Brighton etc have joined the league.
Play in front of an average attendance of 26,000 at home.
Play football that is a joy to watch, managed by (as much as I hate him) positive manager and be challenging for a place in one of the best leagues in the world.
Put yourself in the shop window even if the club doesn't get to the Premier League, if you score goals Premier League clubs will take notice.
So what would you do?