what would you recommend?
My (biased) advice would be to buy the best Carniolan or Buckfast queen on offer at sensible money. My reasoning being based, not on the behaviour of the queen that you buy this year, but on the bees that you will be raising in future years.
Why Carniolan ?
From Gillman 'Practical Bee Breeding': Some Races of the Honey Bee.
Carniolans ... "A cross with the male Carniolan and a queen of another race brings very little improvement, but a cross in the opposite way results in a really good bee".
Then, in future years, as the Carnie genetics become progressively diluted, just top them up again with another Carniolan queen - or live with what you've got if their behaviour is stable.
Alternatively, and assuming you can find one, the Buckfast bee has a good reputation.
With regard to keeping that breed stable, and without recourse to buying-in pure-breds every year or so, Brother Adam gave this advice to an amateur beekeeper in 1981:
"Every year you decide which half of your bees is the least good one. In those colonies you shift queens. You get the queens to put into those colonies by making a daughter queen from each and every one of the colonies in the best half of your colonies. Let the new queens mate in your apiary."
The only thing I think is REALLY important is to let your genetic population stabilise, and not chop-and-change your bee type every few years. I have had to do exactly this several times over the the last few years having purchased so-called 'breeder queens' which turned out to be either mongrels or sub-standard, and removing their genetics from the apiary has been both tricky and hard work (and no doubt incomplete). I eventually purchased Carniolan breeders 'from source' (a certified Slovenian breeder) in order to obtain some 'reference genetics' with which to re-start. So - learn from my mistakes - if you're buying queens to breed from, checkout the seller very carefully before parting with your money.