In Finland, as you all know, there is no wine life outside of ALKO, ALKO being a state owned monopoly. However there are a few ways to get something else (and often much cheaper) from an other shop than ALKO. One of these ways is to visit the Tax-Free shops of the two main ferry companies that connects Finland and Sweden via Ahvenanmaa/Åland.
As I visited recently both of these lines, I can provide you with some advise about the food and wine aspect of the trip. In term of prices, VL is slightly cheaper than TS. In term of service and quality of the stay, TS is above: the boat is more modern, cleaner, bigger. As for food, this gets difficult.
I would say that eating on Silja is a bit better. Not outstandingly better, but a bit. It is also a couple of euro more expensive. For example, the buffet is a bit more varied but the quality is the same (eg the tomatoes-mozzarella are exactly the same). And advantage to Silja for the nicer dining room.
But now we come to our point: the wine. First, in the restaurants.
The wine selection available in the restaurants on TS boats is vast and well priced. However few wines stands out. Many are from mass producers, very little exclusivity. It is rather disappointing when you consider the general standard of the ship, which aims at displaying luxury. VL on the other hand and despite the old fashioned look of the restaurant offers a great if not fantastic selection. Pio Cesare’s Barolo, Dom Pérignon Champagne (at a stunning 94€ the bottle), Zind-Humbrecht… there is no comparison as for the quality of the choice. Clear advantage to VL
When it comes to the duty free, this is utterly a shame for TALLINK-SILJA. VIKING LINE has maybe twice the number of references (and twice less space to display them) and a much more interesting selection. I would advise almost nothing from SILJA. From VL, you can buy Zind-Humbrecht, Remundo Palacios, Taittinger, Dom Pérignon, Pio Cesar or the iconic OCIO by Cono Sur and a bunch of exceptional wines. Almost everything aside the usual basic stuff is worth tasting.
As for spirits, there is again no comparison. SILJA offers mainly second category Cognac and a few standard whiskies when VIKING can provide you with Hennessy XO, Hine XO (a wonderfull and cheap one) as well as Rémy-Martin XO and a big selection of top end whiskies.
So if you are a wine fan, you do not need to hesitate one minute: pick VIKING LINE. But keep in mind that a boat is one of the worst place to store wine, so be careful to choose only the newest vintages are latest releases. The effect of the boat traveling is that the wine ages faster. It is not necessarily a problem in the end but it is something to take into account. I can tell you an interesting story about that. Around 1710 a writer, Barrelier de Bitry, notes that Bordeaux wines (which tended to be harsh in their youth… you can imagine how awful they would taste for us!) gets better after a boat trip. Therefore some Château have shipped wine just for the purpose of aging them better. According to recent experiences, the idea is that 3-6 month on a boat is equivalent to 2-3 years in a cellar. The positive aspect is that wines that require some aging will benefit from the treatment. But cheap, easy drinking wines are likely to get bad faster. On the contrary spirits are not affected by the constant movement of the boat.