I like antennas. A lot. And running only 100 watts – or less, QRP is also fun – it is the antenna that makes the difference.
Most of them are for the shortwave band (2-30 MHz) and, due to size restrictions, most for the upper bands (14-30 MHz). But I sometimes make miniature models of an antenna to evaluate its performance. In that case 433 MHz is a nice frequency that makes any antenna quite small.
Use the “Which antenna” blog entry for a discussion of the antennas individual merits.
For antenna modelling I use MMANA.