I was just curious about the general preferences when it comes to board markup to display variations. Please answer the poll if you would like to share your opinion.

Many reviewers when composing an SGF with variations, use markup to highlight these variations. Also, most SGF editors/viewers automatically place some markup on the board to mark variations of the current move, if not already placed by the SGF composer.
However, this markup often comes in one of two styles:
Children Style: different follow-up moves of the current move are marked
Sibling Style: different alternative moves of the current move are marked

This page describes the difference a bit further:
http://www.red-bean.com/sgf/user_guide/ ... variations

Another alternative is to show no markup on the board for variations, and rely on some other GUI element (like a move tree) to show possible variations.

I think ideally, your SGF viewer would have this as an option you can change to suit your preferences.

No preference as long as it is consistent. I don't want to have one in one view and the other in another viewer because that is confusing.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

Yes, I fully agree. In fact, I'm working on an SGF viewer that already does support both options.

However, this distinction is also important when composing an SGF, particularly in how the style chosen affects how the comments should be made and interpreted. For example, a review composed assuming one style could become confusing/inconvenient if later viewed under the other style, since the comments would no longer align properly with the board markup.

The SGF standard includes a property to specify the variation style assumed by the comments, however some software seems to ignore that and impose their own default.

While I think it is vital to support both styles in go software, in order to accommodate annotated SGF files using either style, I also think that understanding general preferences is still relevant when it comes to the question of which style one should use when composing a review.

There are many more problems than that. For example, if you follow a typical book commentary, where you will often have things like "Black is aiming at a later invasion at A" which expects the letter A to be shown on the board, but if the variation mode uses a, b, c etc (as is often the case) you end up with two As on the board, not necessarily distinguished as upper and lower case. And of course few programs implement the label property properly...

I gave up on sgf commentaries years ago, because it proved totally unworkable.

But if you persist, one thing I feel sure that is needed is a way of STRONGLY reminding the reader where he is, and for that I think you need to show variations on a new board superimposed on (or overlapping with) the main board. The variation board can usefully be coloured or sized differently to alert the user. This idea has been implemented in part in SmartGo books (you click on a hyperlink and a variation board sizable by the editor pops up).