All good suggestions here. I especially like Lola's suggestion of the Premier Inn Waterloo! Walking distance to lots of tourist attractions, cafes and pubs. Easy access to Waterloo Station from there, also, as many of the day trips you may want to take leave from Waterloo. If you plan to do Salisbury and Stonehenge after London, Waterloo is the station you would train out for that.
You are close to the London Eye there, and walking distance to Big Ben, Parliament, and Westminster Abbey.
Holborn is also a good location for many reasons. If you are flying into Heathrow Airport, get on the tube there (Piccadilly Line). This takes you to Holborn. Quick and easy access to your hotel upon arriving. Holburn is close to The British Museum and the British Library. If you have no interest in The British Museum, that removes one of the reasons for staying in Holburn. Holburn is close to Covent Garden, an excellent place to find restaurants.
Victoria area can be very busy, as the Victoria Station and Victoria Bus Station are there. It is walking distance to Buckingham Palace, Big Ben and Parliament, and Westminster Abbey. However, this is an area packed with tourists; elbow to elbow sometimes on the street corners near Westminster Abbey and Parliament. This is an area you can easily get to from other areas of London, as it is well-served by tube and bus routes.
Many tour buses that leave town on day trips are based out of Victoria Station or Coach/Bus Station. If you plan on going on one or more of these tours, it's worth it to stay in Victoria area. The buses leave very early in the morning, and go out for the day to Stonehenge or various castles.
For example, here is a trip to Stonehenge, Salisbury and Bath. Click on the tab above the photo that says "Pick Up Points".
Number 13 on this pick-up location list is Victoria:
https://www.goldentours.com/bath-stonehenge-and-salisbury?agent=SalisburyCathedral
Their Day Trips From London all have a pick up at Victoria Station:
https://www.goldentours.com/day-trips-from-london
London transportation is excellent. No matter where you stay, the tube or bus routes (plus walking) will get you just about anywhere you want to go.