Both cars are very good in their own ways and which ever suits your driving style better you will mopst likely prefer. Maybe best to have ago with both cars if you know people that will let you try them.
I've driven the B44 since the beginning of this season and havn't found a car that I've had a good go with yet that i prefer, you can drive it safe and very fast at the same time and you can really thrash it and be really aggresive with it when you need to/want to, i've found it very forgiving and easy to correct mistakes and a very robust car, (only broken 2 wishbones and 1 shockshaft in a year of weekly indoor and outdoor events!) The B44 like the B4 is one of the easiest cars to get trackside spares and setups/tips for from other drivers and the price of the car is fantastic for what it is and doesnt need any upgrades for it out of the box. Had a small go with a D4 but can't comment much on it, not a car for me thats all I can say, For me it's the B44 all the way for next years season
