It's a real minefield! First of all what DVD standard is your Toshiba? If it's +R then -R won't work. If it's +/- R then they both should, theoretically. However not all DVD R's will be compatible with all players. Just a fact of life!
I bought a trial pack from click here that included 12 different makes. I tried them all and found the one's most suited to my needs. I then stuck with them. These people click here also sell at much lower prices than in the High Street. TDK + or - DVD at 25p each!