With new BDCs coming to the market almost monthly, there are many to choose from depending on your personal investment goals. Personally, I like HTGC, ARCC and SLRC in different degrees and for different reasons, but all have low debt/equity, experienced management, good potential for future cap gains on their portfolio (excepting SLRC) and consistently cover their dividends (excepting SLRC).
The BDC group in my portfolio includes ARCC,AINV,ACAS,PNNT,and SLRC. ACAS is my speculative choice with a cost basis of $1.50/share. The other four are currently long term holds as far as I am concerned. Good hunting to you!