There are many out there who sell antennas they CLAIM are better than the Winegard Batwing.. they lie.. (Well most of 'em but... read on). I've seen some for sale for 100 dollars that.. Well they were 20 dollar table top UHF bowtie antennas from a local hardware or TV store.
Now there are some monster antennas NOT designed for sustained high wind (Designed to go on a tower at home) that are better but they are not practical for RV,
If You have a Winegard Batwing (Sensar II or III) consider getting the Wingman (UHF Director array) and adding it, about 30 bucks. if you have a Sensar IV (Wingman already part of it) you have the best there is.
If you have a 'Jack' antenna.. it is good but not as good as the Winegard.
IF you wish to make additional improvement the Sensar Pro from Winegard works with both the Jack and the Winegard antennas and adds additional amplification to the incoming signal. It replaces the wall plate with the switch LED 12 volt outlet and Antenna connection easy DIY install.
Example of Sensar II or III no wingmanExample of Sensar IV also looks like an II or III WITH the wingman Winegard Sensar Pro, also comes in black