Lake Balaton

I'll spend a few days in Budapest and want to make an excursion to the Lake Balaton. The tour is short enough to make it worthwhile? Would it be better to rent a car or bus travel or train a reasonable alternative?

Lake Balaton is too far for a day trip if you go by public transport, it takes at least 3 hours to get there, if not more.
Unless you rent a car to be a bit pricey, I recommend a day trip to go to Ta³ Velence, a small lake near Budapest. Much better for a day trip because it is much closer. You can take a train from Deli palyaudvar (or Kelenfa¶ld) and it should not take more than 1h to get there (and costs less than a‚¬ 3). It will also be much less touristy.
You can check www.mav.hu for schedules. The site is translated into English.

Balaton is a very popular area for visitors to Budapest. There is a good system of transportation and public welfare facilities and expenses when you get there.
Renting a car would be faster and give you a longer stay for the day, because you can leave early and reduce the end, but a stop for the night there would be much better. There is much to see.
There are many hotels, guesthouses, campsites, or you can hunt in a quiet place of the road and sleep in the car.
Some areas of the lake are not developed at all, just beautiful natural lake and lots of it .. Some parts are a bit gawdy and "resortish ', and have a lot of people, especially on weekends.
The journey takes about 2 hours if you want to see beautiful scenery along the way, or there are visits, often in minibuses, available nearly every day which cost almost as much as renting a car. In a car, you can work around the lake and see the different areas, but the bus or train, you'll be stuck in one place when you get there.
There are frequent trains enough Deli Palyaudvar station on the M2 (red line) directly to Balaton.