Rail from Budapest to Prague

For the lowest price buy from the Czech national railway company at www.cd.cz/en
There are discounts for seniors (65).
There’s usually one morning train with tix for CK 691 or about $30.

You could also look at private operator Regiojet that operate trains between Budapest and Prague. https://regiojet.com/

I am looking for suggestions for the best rail line to travel from
Budapest to Prague.

Thought that this could use some clarification. Generally speaking all the trains are jointly operated by the countries in which they cross or maybe its depart and arrive?

But bottom line is the Czech and the Hungarian site will be selling tickets on the exact same trains, "rail line".

I assume that the prices vary between sellers because of overhead costs. For instance if you are going to Austria the OBB site is quite a bit more expensive than the Hungarian site for the exact same service on the exact same train.

The exception is the RegioJet which is a private company not affiliated with any country's national rail service.

For the lowest price buy from MAV, the Hungarian national railway company at https://jegy.mav.hu/jegy/vonat
Not sure if there are discounts for seniors (65).
There are direct trains about every two hours starting at 8970 ft which is about $25.00

Be sure to get a seat assignment (another $3 more or less)
If you are leaving from Budapest and you buy a MAV ticket the odds of getting help at the station if there should be a problem (doubtful that there would be) is better with the MAV ticket.

I looked at the RegioJet too. Most of the trains are about the same price as MAV, but on the random day I selected they did have one for about $19 that left mid-afternoon. They depart Budapest Deli Station which is about a 20 minute metro or 30 minute tram ride from the center of town. But I have heard nothing bad about the company.

Whoever you buy from, download their app. Much easier for you and the conductor.

HOWEVER: if it were me I would take a discount airline before i sat in a train for 7 hours. Those prices start at about $50 and go up depending on luggage.

I'm doing the reverse in November, from Prague to Budapest. I've chosen the EuroNight Metropol sleeper to save a night of hotel and also for the experience. Booked through the Czech national railway, https://www.cd.cz/ (English site is very easy to use).

If you're new to European train travel, Seat61 has been an invaluable resource:
https://www.seat61.com/trains-and-routes/prague-to-budapest-by-train.htm

Whichever train you choose, make sure you bring water/drink and provisions. We took a direct train from Budapest to Prague in late August and despite services listed on the websites, there was no snack bar, no beverage cart, and no water during the 7+ hour trip. One of the conductors in Slovakia was nice enough to bring out some water from a locked compartment.

There are MANY videos on YouTube covering Budapest => Prague via rail - will give you a good idea of the seating and services.

The Hungariam and Czech railway ticket sites show which trains have food cars (food cars are on all the direct trains that I checked, and most of the others)

Mr. E - If you meant that all direct trains have food cars (as opposed to the sites showing available services on ALL direct trains), we had a direct train and food services were shown (from the websites) to be in effect for our direct train from Budapest to Prague, but there were absolutely none.

BUT!!! The restaurants are always open in the airports (during normal hours). And the flight is a bit faster door to door; and if you pack light no more expensive than a OBB train Budapest to Vienna.

But then again, your carbon footprint will be much lower if traveling by train.

If you're seriously that worried about the lack of food on the train, I've found that at most large European train stations, there's no shortage of grab-and-go options and supermarkets. Just give yourself an extra 20 minutes before boarding.

True. You will most likely be departing from the Eiffel constructed Nyugati pályaudvar. https://youtu.be/OnOsQE-Cgtc?si=CxD1CZSU7Iju3D20

Under the station and extending across both streets that border the station to the shopping mall behind the station is one of the city's largest undergrounds. Plenty of food and yes, even a grocery store as well as a stop of the M3 metro line. https://youtu.be/8S4MKRXrfwg?si=pJWWubSDDNSV7Boa

But, the McDonalds in the station is maybe the most beautiful there is. And if you show up late Friday or Saturday there is a light show and a DJ in the place: https://www.mcdonalds.com/hu/hu-hu/Rolunk/sajtoszoba/sajto-szoba/nyugati-lounge-meki-program.html