ツ≫?妊evian
I should have replied to you much earlier, I'm sorry.

As Luke said, it's up to your personal preference.
If I add some explanation:
ニ停?敞叩ニ断ニ達ニ停ぎ (va-di-mu): or
ニ停?敞叩ニ淡ニ停ぎ (va-dzi-mu)
Originally there's no "di" pronounciation in Japanese (same goes with "ti"), so in the past "di" was written ニ断 or ニ淡, which are comparatively close to the sound of "di".
If you talk with very old people in Japan, some people say
ニ弾ツー not ニ弾ニ達ツー for "tea", for example.
Thesedays, however, there are a lot of loan words from foreign languages and there are more people who are learning English (and other languages), and we try to make the pronunciation and writings as close to the original language as possible.
So strictly speaking ニ停?敞叩ニ断ニ達ニ停ぎ might be more "accurate" pronunciation-wise.
ニ陳照淡ニ停ぎ (wa-dzi-mu)
I believe that V in Russian language (窶曖 in Cyrillic alphabets) sounds a bit softer than V in English, and the name Ivan is traditionally transliterate as
ニ辰ニ陳照停?? not ニ辰ニ停?敞叩ニ停??
Titles of some famous books in Japanese for example.
ニ辰ニ陳照停?懌?堙娯?堙寂?堋ゥ Ivan the Fool by Leo Tolstoy
ニ辰ニ陳照停?慊・ニ辰ニ椎?ニ鍛ニ蛋窶堙固ス竄ャ The Death of Ivan Illyich by Leo Tolstoy
ニ辰ニ陳照停?慊・ニ断ニ男ツーニ箪ニ停?敞達ニ蛋窶堙戸?ェ窶愿コツ One Day in the Life of Ivan Denisovich by Aleksandr Solzhenitsyn
And 窶曖窶柝窶柎窶框窶栲 窶曖窶框窶桀窶樞?樞?樞ぎ窶樞?壺?樞ぎ窶柮窶框窶樞?ー 窶暸窶柝窶桀窶柝窶樞?樞?框窶桎 (Vadim Viktorovich Bakatin) is known as
ニ陳照淡ニ停ぎツ・ニ停?敞達ニ誰ニ暖ニ陳哉停?敞達ニ鍛ニ蛋ツ・ニ弛ニ谷ツーニ蛋ニ停??
(Sorry if it is not a very nice example...)
*I hope you're not offended by my mentioning Russian names - I know Ukraine is an independent country and is different from Russia, but I've heard that Ukrainian language is very close to Russian. (Actually I've been to Kiev once and heard so from my Ukrainian colleague...)